package com.jiyouliang.fmap.util;
import java.io.*;   
    
public class Base64 {   
    private static char[] base64EncodeChars = new char[] {   
        'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',   
        'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',   
        'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',   
        'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',   
        'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',   
        'o', 'p', 'q', 'r', 's', 't', 'u', 'v',   
        'w', 'x', 'y', 'z', '0', '1', '2', '3',   
        '4', '5', '6', '7', '8', '9', '+', '/' };   
    
    private static byte[] base64DecodeChars = new byte[] {   
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,   
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,   
    -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,   
    52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,   
    -1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,   
    15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,   
    -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,   
    41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1 };   
    
    public static String encode(byte[] data) {   
        StringBuffer sb = new StringBuffer();   
        int len = data.length;   
        int i = 0;   
        int b1, b2, b3;   
        while (i < len) {   
            b1 = data[i++] & 0xff;   
            if (i == len)   
            {   
                sb.append(base64EncodeChars[b1 >>> 2]);   
                sb.append(base64EncodeChars[(b1 & 0x3) << 4]);   
                sb.append("==");   
                break;   
            }   
            b2 = data[i++] & 0xff;   
            if (i == len)   
            {   
                sb.append(base64EncodeChars[b1 >>> 2]);   
                sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);   
                sb.append(base64EncodeChars[(b2 & 0x0f) << 2]);   
                sb.append("=");   
                break;   
            }   
            b3 = data[i++] & 0xff;   
            sb.append(base64EncodeChars[b1 >>> 2]);   
            sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);   
            sb.append(base64EncodeChars[((b2 & 0x0f) << 2) | ((b3 & 0xc0) >>> 6)]);   
            sb.append(base64EncodeChars[b3 & 0x3f]);   
        }   
        return sb.toString();   
    }   
    
    public static byte[] decode(String str) throws UnsupportedEncodingException {   
        StringBuffer sb = new StringBuffer();   
        byte[] data = str.getBytes("US-ASCII");   
        int len = data.length;   
        int i = 0;   
        int b1, b2, b3, b4;   
        while (i < len) {   
            /* b1 */   
            do {   
                b1 = base64DecodeChars[data[i++]];   
            } while (i < len && b1 == -1);   
            if (b1 == -1) break;   
            /* b2 */   
            do {   
                b2 = base64DecodeChars[data[i++]];   
            } while (i < len && b2 == -1);   
            if (b2 == -1) break;   
            sb.append((char)((b1 << 2) | ((b2 & 0x30) >>> 4)));   
            /* b3 */   
            do {   
                b3 = data[i++];   
                if (b3 == 61) return sb.toString().getBytes("ISO-8859-1");   
                b3 = base64DecodeChars[b3];   
            } while (i < len && b3 == -1);   
            if (b3 == -1) break;   
            sb.append((char)(((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2)));   
            /* b4 */   
            do {   
                b4 = data[i++];   
                if (b4 == 61) return sb.toString().getBytes("ISO-8859-1");   
                b4 = base64DecodeChars[b4];   
            } while (i < len && b4 == -1);   
            if (b4 == -1) break;   
            sb.append((char)(((b3 & 0x03) << 6) | b4));   
        }   
        return sb.toString().getBytes("ISO-8859-1");   
    }   
}   